In a typical wastewater treatment facility, a population of bacteria is grown and maintained to biologically remove organic pollutants, such as nitrogen or phosphorous, and to reduce the biochemical oxygen demand (BOD) of the wastewater. The bacteria are maintained in reactors holding the wastewater to be treated. Depending on the nature of the bacteria and the desired biological removal that these bacteria perform, the reactors are operated under, for example, aerobic, anoxic, or anaerobic conditions.
Different reactors operating under different conditions may be combined to provide a sequential treatment with successive removal of pollutants. For example, it is possible to combine in series an anaerobic reactor, an anoxic reactor, and an aerobic reactor followed by a final clarifier. Additionally, aerobic mixed liquor can be recycled to the anoxic reactor and return activated sludge can be recycled to the anaerobic reactor.
Further, it is known from U.S. Pat. No. 9,005,442 to equalize a wastewater inflow into a flow equalization reactor to minimize the variations of the wastewater inflow rate into the wastewater treatment facility. Nonetheless, it is desirable to further improve the effectiveness of the treatment process under varying conditions, such as changes in composition of the wastewater and/or of the wastewater inflow rate.